I think you’ve done a great job. There’s a lot of content on there but it navigates easily. I like the drop down menu - I was thinking of doing something not far off similar with a project of my own.
I could comment on the typography… There’s a lot of text - and a lot of text justified centre. I’d of liked to see another font in there to help differentiate between the titles and body copy a bit better. Perhaps using a Serif for the body copy. I think it’d go a long way to help.
The amount of gold throughout the site also feels a little heavy.
Looks like there’s no padding on the text areas here - “Measuring the health of a rare species”. ^
Why are the labels aligned right? ^
^ I think this section could do with a little more work. Perhaps if the heading box “Partners in the Field…” was black? Again, seems like there’s a bit too much gold which dissolves the UI a bit. I’d also align those titles in the content area left.
The “Contact” link could do with some extra padding / margin to the right, to even out the spacing between the links.
Hope some of that helps.